I'm inclined to disagree. Clothing is international trademark Class 25, while sunglasses seem to be treated as belonging in Class 9 as optical equipment. I think your application would be granted, but I'm certainly not 100% sure.

This application will be a problem for you both regards to the USPTO Examiner as well as the mark holder in class 25.

There is a large degree of subjectivity and one does not have to occupy the same class in order to be considered a confusingly similar mark and granted protection from an Examiner in light of a new application. For example, we have Delta Airlines and Delta faucets. They co-exist and the marketplace is not confused because they do unrelated things. But let's say I wanted to open an online plumbing training platform called Delta Plumbing Online. Even if Delta faucets is not filed in that service class, this does not mean that I an not infringing on their mark and they would most definitely have a cause of action against me. This is because the public at large can easily be confused into thinking that they just branched out into the training business.

Further, even if you can advocate the mark through the USPTO successfully you are far from off-the-hook. The competitor is free to file an opposition of just wait until you spend a lot of money and file a petition to cancel later...or worse, just take you to federal court (this option is not likely however straight out of the gate).

Lastly, this is very bad idea from a purely business perspective as well. We "wear" sunglasses just like we wear clothing. Why would you want to enter into your market knowing that your brand may be easily confused with another? And if your answer is that "other" has tremendous brand recognition that will help me sell sunglasses... well, then you just articulated the substance of their legal complaint in federal court.

Anytime you endeavor into investing in a trademark you need to make sure you conduct the proper due diligence and in the US this means both federal and common law. See this link for a nice overview of this process: http://www.lanternlegal.com/trademark_due_diligence.php.

If you would like to discuss further over a free phone consult, feel free to contact me anytime that is convenient.